Correlation Between the Laser-Induced Breakdown Threshold in Solids, Liquids, and Gases

A simple theoretical expression is developed which allows correlation between laser-induced breakdown threshold in solids, liquids, and gases. It is shown that the breakdown threshold for single-layer thin films, surfaces of dielectrics, the bulk of solid dielectrics, linear liquids, and gases all follow a linear fit to the expression N2/3/(n2-1), where N is the atomic number density and n is the refractive index. The threshold for sol-gels is compared with conventional thin film thresholds and is shown to agree reasonably well with the relative threshold predicted by the simple expression. The gas breakdown threshold vs pressure is compared with the predicted dependence. Finally, maximum values for solid, liquid and gas thresholds are plotted against the expression and are seen to fall on a single straight line across three decades of physical constants.